1. Field of the Invention
The present invention relates to a portable sawmill and more particularly to a sawmill of the type employing a chain saw. In addition, the invention relates to a method of cutting logs in which the cutting edge of a chain saw is maintained substantially in alignment with the longitudinal axis of a log during cutting.
2. Description of the Prior Art
It is and has been common practice to leave large numbers of short and small logs behind at a logging site because it is not economically feasible to transport them to a sawmill. This material is typically burned as slash or simply allowed to rot. Devices have been made to salvage some of this otherwise lost wood at the logging site. In particular, various types of portable sawmills have been developed for transportation to a logging site for milling logs that otherwise would be left behind. Of these sawmills, only a few are known which utilize a chain saw for purposes of cutting lumber. In one device, shown in U.S. Pat. No. 3,695,316 of Pluckhahn, a portable timber milling jig includes a stationary beam for positioning parallel to and above a log. A chain saw carriage is mounted to the beam and can slide along the beam with the chain saw projecting downwardly for cutting slabs of wood from the log. As with other known chain sawmills, the cutting edge of the saw of this device is generally normal to the log being cut. Consequently, sawdust is produced during cutting and not more desirable elongated wood fibers. Furthermore, the Pluckhahn device lacks the capability of cutting slabs that are of non-uniform thickness.
Another portable chain sawmill device is described in U.S. Pat. No. 2,702,057 of Miller. In Miller, the chain saw cutting edge is held at an angle approaching normal to the log so that sawdust and not elongated fiber is produced during cutting. Also, Miller employs an overhead carriage along which the saw is moved from one end of the log to the other during cutting. Limitations in this sawmill interfere with the cutting of canted slabs from a log.
Therefore, a need exists for a portable chain sawmill which produces elongated fibers as usable by-products during cutting, and which has the flexibility of easily cutting lumber of uniform thickness or which is tapered as desired.